“The HK P9 is a semi-automatic pistol from Heckler & Koch in 9×19mm Parabellum and the first to use a variation of H&K’s roller delayed blowback system in a pistol format and polygonal rifling now common in H&K designs. Design began around 1965 and production ran between 1969 and 1978. Only 485 single-action P9’s were produced and were discontinued in 1970. A traditional double action version, the P9S (the S standing for Spannabzug, or “double-action trigger”) was manufactured in greater numbers.” read entire description here